My Science School

 

Many plants cannot grow or make seeds if their stems and leaves have been torn off or eaten by an animal. Some plants have leaves that taste bitter. Other plants have thorns, prickles or sharp leaves to keep them safe.

 

 

 

 

 

 

This plant has thorns to keep animals away.

If plants are to stay alive they have to protect themselves. Some plants do this by having prickly thorns. Thorns are special short, sharp branches. Other plants, such as holly, protect themselves by having spiny leaves. If an animal tries to eat a spiky plant, it will soon be scared off!

 

Continue reading "Plant protection"

 

 

 

All living things need water. Plants drink by sucking up water with their roots. Water travels up the stem to the leaves. If a plant does not have water the stem will go floppy. The leaves and stem will dry out and the plant will die.

 

 

 

 

 

 

Plants need a little water, but not too much.

If plants do not have water they dry up and die. Indoor plants need to be watered, but too much water can be bad for them. If they are too wet the plants will rot. A plant’s roots have thin ‘hairs’ at the end of them. It is these root hairs that absorb water. The main roots then carry the water up to the plant.

 

 

 

 

 

 

 

In summer, people may need to water plants that grow outside.

Plants lose water through their leaves. When the weather is warm and dry, plants lose more water than usual. They need to drink extra water to stay alive. If there is too little rain, gardeners need to water their plants.

 

 

 

 

 

 

 

See how plants drink! The water travels up the stem to the leaves.

Put a few drops of food colouring into a glass of water. Ask an adult to cut a stick of celery. Put it in the coloured water. Look at the celery after 30 minutes. Does the coloured water move up the stem toward the leaves? Cut the celery in two. Can you see the tubes holding the water?

 

 

 

 

 

Plants need sunlight, air and water. Most plants have roots to hold them in the ground and to suck up water. They have stems to hold up their leaves. Most plants have green leaves. They use their leaves to make food.

 

 

 

 

 

 

This plant has roots a strong stem, and green leaves.

All living things, including plants, have seven things in common. They are – feed, move, breathe, get rid of waste products, and grow, sensitive to things like light and heat, and they make new versions of themselves.

 

 

 

 

Continue reading "Plants are living things"

Some plants are so small they are hard to see. Some are so big they seem to touch the sky. Plants grow in many places. If you look you will find plants around your home and school, as well as in parks and in the country.

Here are some tiny plants and a very tall tree

Plants have been on planet Earth for 400 million years. They even existed before dinosaurs! Today, scientists think there are as many as ten million different kinds of plants. Some plants die after a few days and others live for hundreds of years.

 

 

 

 

 

 

 

 

 

 

Continue reading "The plant world"

 

Nuclear power is made without burning fuels that release harmful gases. Some people argue that nuclear power is also cheap because only small amounts of fuel are needed to create lots of energy.

 

 

 

 

1 kg of uranium produces as much energy as 3,000 tonnes of coal!

When the nucleus of some materials – such as uranium – is broken up, a huge amount of energy is released. Nuclear power stations only use a small amount of fuel, unlike the large quantities of coal, gas and oil needed to make electricity. This could make nuclear power a cheap source of alternative energy.

 

 

 

 

 

 

Once a nuclear reactor has been built, it can make cheap electricity.

We are using more and more energy but we are running out of fuels that make electricity, such as coal, gas and oil. As they run out, these fuels are becoming more expensive. Nuclear reactors are very expensive to build, but they only use a small amount of fuel.

 

 

 

 

Nuclear power does not release harmful gases.

When we burn fossil fuels we release harmful gases into the air. The gases trap heat around our planet, which is causing global warming. Nuclear power does not produce this type of pollution.

Continue reading "The advantages of nuclear power"

 

 

Many people worry about the safety of nuclear energy and the radiation it produces. There are also concerns about how to safely throw away or reuse radioactive waste material.

 

 

 

 

 

 

 

Workers in a nuclear power station need to wear special clothing.

Radiation can make people very ill. Strict safety producers need to be used in a nuclear power station. Special clothing protects workers from the radiation. Many people believe that radioactive materials cause disease and disabilities in people and animals living nearby.

 

 

 

Continue reading "The disadvantages of nuclear power"

 

 

Nuclear accidents have been caused by leaking pipes and equipment that has broken down. If radiation leaks, it can travel very far, harming people and the natural world. Power stations are now built to very high safety standards.

 

 

 

 

 

 

 

Nuclear reactors can overheat and burn.

If a nuclear power station overheats, it can lead to a meltdown. This is when the nuclear reactor burns and becomes so hot that it melts. Equipment explodes and the heat is so intense that even concrete walls burn. A meltdown can allow deadly radioactive materials to escape, killing anything nearby.

 

 

 

 

Human error caused the world’s worst nuclear disaster at Chernobyl, Ukraine.

 In 1986, mistakes by workers caused a meltdown at the Chernobyl nuclear reactor. An invisible cloud of poisonous radiation spread for many kilometres. Today, more advanced machinery can help prevent this kind of disaster.

 

 

 

 

Nuclear radiation can kill.

The powerful radiation from nuclear fuel can cause illness and death to people and wildlife. The children of people exposed to radiation may be born with illnesses and disabilities. However, it is not always easy to prove the link between radiation and ill health.

 

 

 

 

There are many safeguards to make sure that nuclear power stations stay safe and secure. Safety procedures are constantly checked. Special containers are also used to carry the nuclear fuel or waste to and from the power station.

 

 

 

 

 

 

Special machines test for levels of radiation.

Everyone who works in a nuclear power station or with nuclear fuel is regularly tested to check levels of radiation. Machines called Geiger counters can work out if the levels of radiation in a person’s body are safe. Even clothes and masks are tested!

 

 

 

 

 

Transporting nuclear fuel is dangerous.

There are only a few countries where factories can reuse nuclear fuel rods. Old and used fuel rods are shipped by sea or driven long distances to be processed. The fuel rods must be carried in specially built containers that will not burn or crack.

 

 

 

 

 

Nuclear power stations are surrounded by thick walls.

Power stations cover hundreds of square metres. The reactor is surrounded by thick concrete and steel walls to prevent dangerous fuel leaks. But many people believe nuclear power stations will never be safe enough.

 

 

No one knows what to do with waste from a nuclear reactor. Nuclear power stations have to deal with materials that cannot be used again. The problem is that nuclear waste can remain radioactive for thousands of years.

 

 

 

 

 

 

 

Used fuel rods take years to cool down.

When fuel rods cannot be used any longer, they are cooled in special ponds in the nuclear power station to allow their heat and radioactivity to decrease. It can take up to 50 years for them to cool down! After this time, they are chopped up and dissolved in acid so that they can be disposed of more safely.

 

 

 

 

Continue reading "Nuclear waste"

 

 

 

Accidents have made nuclear power unpopular. But we are in danger of running out of fossil fuels. Some people think that nuclear power is the most reliable alternative to coal, gas and oil. It is argued that nuclear power also causes less pollution than fossil fuels.

 

 

 

 

 

 

 

 

Nuclear power plants supply about 17% of the world’s electricity.

Some countries, such as France, depend on nuclear energy for most of their electrical supply. Other countries, such as the US, the UK and China, have mainly used coal and oil to produce their electricity. However, these countries are beginning to look again at nuclear energy as an option for the future.

 

 

 

 

 

New power stations are being developed.

Scientists are trying to make nuclear energy safer. Some nuclear reactors now use laser beams to produce a nuclear reaction. Small amounts of fuel are needed and the reaction only works under certain conditions.

 

 

 

 

 

Some countries are using other forms of energy.

Some countries, such as Germany are using less nuclear power. They are now turning to other forms of energy, such as wind and solar power. These sources only produce small amounts of energy but they are safe, widely available and cause less pollution.

 

 

Nuclear power may become more popular in the future. Oil and gas will run out one day because developing countries are using more and more electricity. We must therefore find alternative energy sources.

 

 

 

 

 

In 50 years’ time, nuclear energy may be made in a different way.

Most nuclear reactors use fission to make energy. Another way to create nuclear energy is to join atoms together. This is called fusion, and produces much less radiation than fission. Fusion takes place in special doughnut-shaped reactors called tokomaks, but so far scientists have not found a way of producing enough energy from fusion.

 

 

 

 

 

 

Nuclear reactors could send spacecraft to other planets

Small nuclear reactors could provide enough to power a spacecraft. However, people argue that it would be dangerous to launch nuclear materials into space.

 

 

 

 

 

 

 

Nuclear waste may be a problem for your children and their great-great-grandchildren.

Dumping nuclear waste may solve the problem for now, but how will future generations deal with the waste? Scientists have suggested writing instructions on special paper that does not rot. This paper is similar to the papyrus used by Ancient Egyptians thousands of years ago.

 

 

The most terrible and destructive weapons are made from nuclear energy. These are nuclear or atomic bombs. So far, nuclear bombs have only been used a few times but they have caused the deaths and illnesses of hundreds of thousands of people.

 

 

 

 

 

 

 

 

This woman is suffering from radiation from a nuclear bomb.

During the Second World War, American pilots dropped a nuclear bomb on the Japanese city of Hiroshima. It killed 100,000 people. Another bomb killed 75,000 people in the city of Nagasaki. People in these cities continue to suffer from illnesses caused by the radiation.

 

 

 

 

 

 

 

 

Many leaders have agreed not to use nuclear power to make weapons.

Some people think that nuclear weapons should be destroyed to stop people using them. Others argue that owning nuclear weapons prevents wars, because people will be afraid of the weapons being used.

 

 

 

 

 

 

Nuclear weapons contain deadly plutonium.

When uranium is used to make nuclear energy, a material called plutonium is produced. This is one of the most toxic substances known to humans. Plutonium has been used to make nuclear weapons and can destroy a population within minutes.

 

Nuclear energy has many other uses. Small amounts of radioactive materials can detect illnesses and cure some diseases. Some hospital equipment is also kept especially clean or sterilized with radiation.

 

 

 

 

 

 

 

 

Radiation can be used to kill germs in food.

Radiation can be passed through food to kill germs. This makes the food last longer. Astronauts eat radiated food to prevent them from becoming unwell in space. However, some people argue that because we don’t know the effects of radiation on the body, it is unhealthy to radiate food.

 

 

 

Continue reading "Other uses of nuclear energy"

 

 

 

Today, nuclear power is mainly used to make electricity. This is usually cheaper than the electricity made from burning fuels such as coal, oil or gas. Some people say that nuclear energy is cleaner because it does not produce smoke.

 

 

 

 

 

 

 

These stored uranium fuel rods can be used to make electricity.

A nuclear reactor is a large tank or building inside the power station. Here, pieces of powdered uranium are put into special fuel rods. These are gathered into bundles and placed in the centre of the reactor. The fuel rods make the atoms split to release energy that is then used to heat water.

 

 

 

Continue reading "What are the uses of Nuclear energy?"

 

 

All about uranium

The fuel used to produce nuclear power is called uranium. It is found in rocks in the ground. Uranium is a heavy silvery metal. It can be mined and made into nuclear fuel. The atoms in some types of uranium are easier to break up than some other substances.

 

 

 

 

Uranium is processed in a factory.

Uranium is found deep in the ground. Miners dig out and crush rocks containing uranium. They use an acid to separate the uranium from the rest of the rock. The uranium is then turned into a gas and then into a powder. These processes enrich the uranium so that it can be turned into nuclear fuel.

 

 

 

 

 

 

Uranium came from exploding stars!

Scientists believe uranium was formed when old stars exploded over six billion year ago. The uranium dust from the stars scattered throughout the Universe, eventually settling in rocks deep inside planet Earth.

 

 

 

 

 

 

Uranium is radioactive.

A radioactive substance gives off invisible rays of energy called radiation. These rays cannot be seen, tasted or felt. Uranium’s radioactivity provides some of the heat inside the Earth. This is spread out over huge areas and is harmless. However, radioactivity from nuclear fuel is more concentrated and can be very dangerous.